Electric plug with blades having elements for piercing and clamping insulated cords



Aprnl 22, 1952 J. A. GALVAO 2,593,743

- ELECTRIC PLUG WITH BLADES HAVING ELEMENTS FOR PIERCING AND CLAMPING INSULATED CORDS Filed Nov. 50, 1950 3 INVENTOR.

ose/ 14 A. GALVAO A2 fiww.

ATTORNEY extremity with a pointed, claw-like projection or spur 2| adapted to pierce the insulation of conductor wires |2 when said prongs are inserted within each pair of channels l1 and pressed downwardly upon said conductor wires in a manner to be more fully described hereinbelow. The spur 2| is defined by slits 2|a which lead from the lower end of the outer edge or recess 22a and also from the outer wall with arms 22 disposed at opposite sides of the spur 2|. The arms 22 have their lower outer ends formed with arcuate edges 22b and forming portions of the recess 22a at the inner lower end of the outer leg llb for locating and receiving each insulator wire l2 and the outer arcuate edges 22b of the arms 22 have their lower portions or arms 22 moved inwardly or towards one another by-the V-shaped bottom of the channel I! so that the arcuate edges 22b act as cam surfaces when the prongs I are forced downward into the channels IT. The lower end of. inner leg ||a is formed with an integral upwardly bent lug 23 for firmly anchoring the contact prong within the plug body Ill, said upwardly bent lug being so arranged as to abut inner shoulder |8a of central portion l8 of plug body when the contact prong has been fully inserted and pressed downwardly within each pair of channels Each prong may be further provided with the conventional opening 24 to assure positive contact with the terminals of an electrical outlet (not shown).

In actual use the conductor cord carrying separate conductor wires I2 is passed into the plug body l0 through the central opening l3 after which each separate conductor wire |2 carrying its insulation |2a is directed by the V-shaped member to the right and left and disposed within each of the vertical grooves l5 with the top of each of said wires preferably extending slightly beyond the top surface of plug body H] as illustrated in Figs. 1 and 2. 7

Each contact prong H is next inserted within a pair of channels IT with the conductor wires |2 carrying its insulation |2a interposed between groove l5 and the outer leg II) of prong H Each of said prongs is pushed down until the pointed projection or spur 2| pierces through the insulation |2a of conductor wires l2 and makes firm contact with the said conductor wires, portions of said wire entering the slits 2|a and being wedged between the pointed projection 2| and the adjoining arms 22 of outer leg III) as clearly indicatedin Fig. 5. At this point upwardly bent lug 23 of inner leg ||a passes below central portion |8 of plug body H1 and into abutment against internal shoulder |8a thereof to firmly. and irremovably secure the contact prong However, if'desired, a transverse slot |8b may be formed in central portion |8 to allow insertion of a pointed instrument for bending back upwardly bent lug 23 for the removal of contact prong M.

It is important to notethat each of the vertical channels extends for a short distance below the top surface of shoulder-wall, l6, as shown in Fig. 3, and that the outer leg Nb of contact prong l has a conductor-receiving notch 22a so that when the prong II is fully entered within plugbody ID with the conductor wire |2 carrying its insulation |2a interposed between the outer wall I lb of said prong and the concave groove I5 of said plug body, the, terminal end portions of outer leg ||b (shown in'dotted outline in Fig- 5) will lie partially below shoulder wall l6land projection 2| having penetrated or I pierced the insulation Ila ofconductor wires l2,

the arms 22 will be forced towards each other by action of their cam surfaces or arcuate edges 22b upon the V-shaped bottoms of channels l1 and the wires will be tightly gripped between prong 2| and the arms 22 of outer leg I lb to assure firm and positive contact.

Contact prongs may, of course, be formed from a single thickness of conducting metal rather than having the double-walled construction illustrated in the accompanying drawing and the upwardly bent lug 23 and pointed projection 2| may be formed integrally therewith. Also, the contact prong may be formed with a plurality of projections, if desired, rather than with a single projection as illustrated.

Since certain additional modifications may be made in the electric plug of my invention without departing from the scope thereof, it is intended that all matter contained in the foregoing description and shown in the accompanying drawing be interpreted merely as illustrative and not in a limiting sense.

I claim:

1. In an electric plug, a body ofinsulation formed with a wire-receiving bore and with sockets open at their outer ends and at their inner ends communicating with the bore and having bottoms formed with walls disposed at an incline, the said sockets having opposed side walls formed with grooves extending from the open outer ends of the sockets to a point below the bottoms thereof, electric wires extending through said bore into said sockets and having portions disposed along the bottoms of the sockets, and contact prongs inserted longitudinally into said sockets through the open ends thereof with their side edges engaged in the grooves of the sockets, each prong having its inner end portion formed with slits leading from its inner end and defining a spur between the slits tapered to a point at its lower end and arms at opposite sidesof the spur, the arms having lower ends of their outer side edges extending at an inward incline and constituting cam surfaces, the spurs of said contact prongs penetrating the wires and portions of the wires being engaged in the slits, the arms extending below the bottoms of the sockets and bent towards the spur by action of their cam surfaces upon the inclined walls of the bottoms of said sockets and thereby moved into gripping engagement with the portions of the wires in the slits.

2. In an electricplug, a body of insulation formed with a wire-receiving bore and with sockets open at their outer ends and at their inner ends communicatingwith the,bore and having transversely V-shaped bottoms, electric wires extending through the bores and into said sockets across bottoms thereof, and contact prongs thrust into said sockets through the open outer ends thereof, each prong having a longitudinally extending spur midway the width of its inner end and longitudinally extending arms at opposite sides of its spur, outer side edges of said arms having lower portions disposed at an inward incline and constituting cam surfaces and lower ends of the arms having edgesextending upwardly atan inward incline towards the lower end of the prong for centering a'wire under the spur when the contact is thrust into a socket and its inner end having straddling engagement with the portion of the wire extending across the bottom of the socket, said prongs having their spurs penetrating the wires and their arms forced towards each other by action of their cam surfaces upon the V-shaped bottoms "of said sockets and into gripping engagement with portions of the wires between the companion spurs and arms.

3. In an electric plug, a body of insulation formed with a wire-receiving socket open at its outer end and its bottom formed with oppositely disposed inclined portions, and a contact prong inserted into said socket through the open outer end thereof, said contact prong having at its inner end a spur tapered to a point for penetrating a conductor wire and arms at opposite sides of said spur formed along their outer side edges with downwardly converging cam surfaces for engaging said oppositely disposed inclined portions of the body and serving to bend the arms towards opposite side edges of the com- 15 2,

6 panion spur and into gripping engagement with portions of the wire penetrated by the spur when the prong is forced into the socket and into engagement with the inclined portions of the bottom of said sockets.

JOSEPH A. GALVAO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,301,919 Petry Nov. 1'7, 1942 Orlando Aug. 15, 1950 

